2026-07-072026-07-07http://salesiana.dossiersoluciones.com/handle/123456789/203519We revisit a weak gravitational lensing problem by constructing a setup which describes the actual system as accurately as possible and solving the null geodesic equations. Details are given for the case of a Universe driven only by a cosmological constant, Λ, which confirm the conventional results: The conventional lensing analysis is correct as it is, without any need for correction of O(Λ). We also treat the cases of the lensing in generic FRW backgrounds.6 pages, the discussion is revisedAstrophysicsGeneral Relativity and Quantum Cosmologytext